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Horsetail (Equisetum) Plants

Horsetails are hollow-stemmed plants that belong to the genus Equisetum, the only remaining genus of a large group of primitive vascular plants. Sometimes alternatively known as mare's tail, horse pipes, or snake grass, horsetails are characterized by an extensive creeping, root system that anchors them firmly deep into the ground.

In the Carboniferous period, relatives of extant horsetails grew to tremendous proportions and contributed greatly to coal deposits. Fossil evidence suggests that extinct horsetails were more similar in appearance to trees than those that are currently living. Most prevailing species of horsetail, which may be found in all temperate and tropical regions except New Zealand and Australia, do not grow more than three feet high. However, some may still achieve impressive lengths, especially a tropical American species known as E. giganteum that may grow more than 30 feet long.

Although many horsetails have little commercial value, some have been utilized by humans for thousands of years. The horsetail scientifically described as E. arvense has been used as an herbal remedy since the early days of ancient Greece and Rome. Traditionally the plants were employed to promote blood clotting and to treat kidney infections and tuberculosis. Another useful type of horsetail is commonly known as the scouring rush. The coarse, textured plant contains a significant amount of silica granules in its cells that make it a valuable for scouring or as an ingredient in abrasive powders.